This would probably force Mr Turnbull to call an election. Mr Joyce said he was “shocked” to learn he might be a New Zealander and refused calls to resign, even though two Greens MPs resigned last month after learning they were dual citizens.

He said he had referred the matter to the High Court and had been asked by Mr Turnbull to stay on until his fate was decided.

"Neither I, nor my parents have ever had any reason to believe I may be a citizen of another country,” he said.

Bloody hell. After all those times Barnaby Joyce was red-faced, ranting and raving in Parliament he was actually doing a haka #auspol#nz

Mr Joyce, leader of the rural-based National party, the junior partner in the ruling conservative Coalition, is the most senior MP to be embroiled in the crisis.

Barnaby Joyce taking the oath of office as he is sworn in at Government House in Canberra in July 2016Credit:
AP

A colourful figure, he famously threatened to kill Pistol and Boo, the pet dogs of Depp and his ex-wife Heard, after the celebrity couple smuggled the Yorkshire terriers into the country without clearing customs in 2015.

Mr Turnbull insisted he was confident that Mr Joyce would be ruled eligible, saying this was based on advice from the solicitor-general. But some legal experts said the constitution was clear and Mr Joyce may not survive.

Labor MP yells at Barnaby Joyce who stand to answer a question: “Breached as bro!"